2. Oxyria. Sepals 4. Stigmas 2. Achene orbicular-winged. Leaves reniform.
3. Rumex. Sepals 6. Stigmas 3. Achene 3-angled.
[++][++] Sepals 5 (sometimes 4), equal and erect in fruit. Achene triangular or lenticular.
4. Polygonum. Embryo slender, curved around one side of the albumen. Pedicels mostly fascicled.
5. Fagopyrum. Embryo in the albumen, its very broad cotyledons twisted-plaited.
6. Polygonella. Embryo slender, nearly straight. Pedicels solitary. Leaves jointed at base.
[+][+] Stipules obsolete; ovule hanging from the apex of a slender stalk.
7. Brunnichia. Calyx 5-parted, in fruit with a wing decurrent on the pedicel. Tendril-climber.
1. ERIÓGONUM, Michx.
Flowers perfect, involucrate; involucre 4–8-toothed or lobed, usually many-flowered; the more or less exserted pedicels intermixed with narrow scarious bracts. Calyx 6-parted or -cleft, colored, persistent about the achene. Stamens 9, upon the base of the calyx. Styles 3; stigmas capitate. Achene triangular. Embryo straight and axile, with foliaceous cotyledons.—Annuals or perennials, with radical or alternate or whorled entire leaves, without stipules. (Name from ἔριον, wool, and γόνυ, knee.)